Motor-operated valve

ABSTRACT

An electrically operated valve having excellent wear resistance while suppressing cost is provided. The electrically operated valve comprises a valve main body having a valve seat; a motor including a stator fixed to the valve main body and a rotor driven to rotate with respect to the stator, a planetary gear type deceleration mechanism configured to decelerate rotation of the rotor to transmit to an output gear, a valve member configured to be movable toward and away from the valve seat in an axial direction, and a feed screw mechanism configured to convert rotational movement of the output gear into movement of the valve member in the axial direction. The planetary gear type deceleration mechanism includes a sun gear coupled to the rotor, a planetary gear engaged with the sun gear, a carrier for rotatably supporting the planetary gear, an annular ring gear engaged with the planetary gear, and a sliding member abutting against an axial end of the sun gear. The output gear has a different number of teeth than the ring gear, and engages with the planetary gear, and the sliding member is made of a different material from the material of the sun gear.

This Application is continuation of U.S. patent application Ser. No.16/649,270 filed Mar. 20, 2020, which is a 371 of PCT/JP2018/035358filed on Sep. 25, 2018 which, in turn, claimed the priority of JapanesePatent Application No. 2017-187679 filed on Sep. 28, 2017, the aboveapplications are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to an electrically operated valve, and,for example, to an electrically operated valve incorporated in arefrigeration cycle and used for controlling the flow rate of a fluidsuch as a refrigerant.

BACKGROUND OF THE INVENTION

Conventionally, as a so-called electrically operated valve for openingand closing valves using an electric motor, there is known a valve whichis opened and closed by directly transmitting the rotation of a rotor toa screw mechanism. There is demand for such electrically operated valvesto open and close valves under higher load conditions, or to furtherimprove the angular resolution of the valve opening degree.

With respect to this, as illustrated in Patent Document 1, the presentapplicant has proposed an electrically operated valve in which therotation of the rotor is decelerated by a planetary gear typedeceleration mechanism and transmitted to a screw mechanism. Since thetorque per unit rotation of the rotor becomes large in such anelectrically operated valve, it can be used even under high loadconditions, and the angular resolution of the valve opening degree persingle drive pulse can be increased.

CITATION LIST Patent Literature Patent Document 1: Japanese Patent No.4,817,671 SUMMARY OF INVENTION Technical Problem

Incidentally, in planetary gear type deceleration mechanisms in whichthe lower surface of a sun gear member formed integrally with the upperend of a sun gear faces an upper surface of a ring gear, due to thisstructural configuration, sliding occurs when both come into contact. Onthe other hand, from the viewpoint of cost reduction, it is generallypreferable to form the sun gear and the ring gear from a resin material.However, if the lower surface of the sun gear member and the uppersurface of the ring gear formed of the same resin material are slidtogether, the relative speed between the sliding surfaces of thesemembers is high, and therefore there is a risk of causing prematurewear. Therefore, in Patent Document 1, a leaf spring is installed tourge the sun gear member in one direction to separate the sun gearmember from the ring gear. However, from the viewpoint of costreduction, there has been a demand for removing this leaf spring.

It is an object of the present invention to provide an electricallyoperated valve that has excellent wear resistance while also suppressingthe cost.

Solution to Problem

In order to achieve the above object, the electrically operated valveaccording to the present invention includes a valve main body having avalve seat, a motor including a stator fixed to the valve main body anda rotor driven to rotate with respect to the stator, a planetary geartype deceleration mechanism configured to decelerate rotation of therotor to transmit to an output gear, a valve member configured to bemovable toward and away from the valve seat in an axial direction, and afeed screw mechanism configured to convert rotational movement of theoutput gear into movement of the valve member in the axial direction,wherein the planetary gear type deceleration mechanism includes a sungear coupled to the rotor, a planetary gear engaged with the sun gear, acarrier for rotatably supporting the planetary gear, an annular ringgear engaged with the planetary gear, and a sliding member abuttingagainst an axial end of the sun gear, the output gear has a differentnumber of teeth than the ring gear, and engages with the planetary gear,and the sliding member is made of a different material from the materialof the sun gear.

The sliding member is preferably an annular body disposed between thesun gear and the carrier and is configured to slide with respect to atleast one of them.

The sliding member is preferably an output shaft configured to slidewith respect to the axial end of the sun gear, and is connected to theoutput gear to transmit a rotational force to the feed screw mechanism.

It is preferable that the sun gear is made of a resin material, and thesliding member is made of a metal, ceramic, or glass material.

Advantageous Effects of Invention

According to the present invention, it is possible to provide anelectrically operated valve that has excellent wear resistance whilesuppressing the cost.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an overall longitudinal cross-sectional view illustrating anelectrically operated valve according to the present embodiment.

FIG. 2 is an exploded perspective view of a planetary gear typedeceleration mechanism used in the electrically operated valveillustrated in FIG. 1.

FIG. 3 is an exploded perspective view of the planetary gear and carrierof the planetary gear type deceleration mechanism illustrated in FIG. 2.

FIG. 4 is an enlarged view illustrating the inside of a can 30 in theconfiguration of FIG. 1.

FIG. 5 is a cross-sectional view similar to FIG. 4 of an electricallyoperated valve according to another embodiment.

DESCRIPTION OF EMBODIMENT(S)

Hereinafter, an electrically operated valve according to an embodimentof the present invention will be described with reference to thedrawings. It should be noted that in the following description of theembodiments and comparative examples, parts and members having the samefunctions are denoted by the same reference numerals, and redundantdescription of parts and members denoted by the same reference numeralsis omitted.

(Definition of Different Materials and Axial Direction)

Here, when “adhesion wear” occurs when two members are slid together,the material on which those members are formed is referred to as thesame type of material. Further, a “different material” refers tomaterials which are not the same material; that is, when “adhesion wear”does not occur when two members are slid together, the material of onemember corresponds to a different material with respect to the materialof the other member. Examples of different types of materials includematerials of different categories when arbitrary materials areclassified into categories such as, for example, metals, resins,ceramics, glass, and the like. In addition, the “axial direction” hereinrefers to the axial direction of the valve main body.

Embodiment 1

FIG. 1 is an overall longitudinal cross-sectional view illustrating anelectrically operated valve according to the present embodiment. FIG. 2is an exploded perspective view of a planetary gear type decelerationmechanism used in the electrically operated valve illustrated in FIG. 1,but a part thereof is cut away to facilitate better understanding. FIG.3 is an exploded perspective view of the planetary gear and the carrierof the planetary gear type deceleration mechanism illustrated in FIG. 2.

The electrically operated valve 1 includes a drive unit 1 a that isoperated by an exciting action and which includes a motor composed of astator 2 and a rotor assembly (hereinafter also called a motor) 8, agear deceleration unit 1 b which receives a rotational driving forcefrom the drive unit 1 a and performs gear deceleration to output adecelerated rotational force, and a feed screw mechanism 1 c whichconverts the rotation decelerated by the gear deceleration unit 1 b intoa displacement in the axial direction using a screw action and outputsthe displacement in the axial direction.

The can 30 is an air-tight container fixed to the valve main body 10 viaa bearing member 68, and has a thin-walled cylindrical shape with a top.The drive unit 1 a includes a stator 2 and a permanent-magnet type rotorassembly 8 which is rotationally driven by the stator 2. The stator 2 isan exciting device for an electric motor, and is fixedly disposed on theouter peripheral portion of the can 30 and is formed by molding a coil140 wound around a bobbin integrally with resin. The rotor assembly 8 isrotatably supported inside the can 30. The stator 2 and the rotorassembly 8 constitute a stepping motor as one example of an electricmotor.

The stator 2 is detachably fitted to the can 30 by a mounting bracket180 formed of a leaf spring. In this example, the dome portion 102formed in the can 30 is elastically fitted into a hole 182 formed in themounting bracket 180, thereby positioning the stator 2 relative to thecan 30. Coils 140 are supplied by an external power source via a lead142 for excitation of the stator 2.

The valve main body 10 includes a valve chamber 14 formed therein, andalso a bottom portion 15 formed with an orifice 16 that opens to thebottom surface of the valve main body 10. A pipe 22 that communicateswith the side surface of the valve chamber 14 and a pipe 20 thatcommunicates with the lower end of the orifice 16 are fixed to the valvemain body 10.

The gear deceleration unit 1 b is composed of a planetary gear typedeceleration mechanism (hereinafter abbreviated as a “decelerationmechanism”) 40 for decelerating the rotational speed of the rotorassembly 8.

As illustrated in FIG. 2, the deceleration mechanism 40 includes a sungear 41 integrated with the rotor assembly 8, a plurality (three in thisexample) of planetary gears 43 engaged with the sun gear 41 that areelongated in the axial direction and rotatably supported by a carrier 42formed by molding plastic, for example; a ring gear 44 that is arrangedconcentrically with the sun gear, fixedly supported with respect to thevalve main body 10, and engaged with a part (the upper portion) of eachplanetary gear 43; and an output gear 45 formed in a cylindrical shapewith a bottom that has a number of inner teeth slightly different fromthe number of teeth of the ring gear 44 (that is, in a profile-shiftedrelationship with the ring gear 44). The sun gear 41, the carrier 42,the ring gear 44, and the output gear 45 are formed of polyphenylenesulfide resin (PPS).

In FIG. 3, the carrier 42 includes a lower disk 42 b formed byimplanting three column portions 42 a in parallel on the outer peripheryof the upper surface, and an annular plate 42 c. A cylindricalprotrusion 42 d is formed on the upper end of each of the column portion42 a, and three corresponding through holes 42 e are formed in the plate42 c.

On the other hand, the planetary gear 43 formed of a zinc alloy hascylindrical convex portions 43 a (only the upper end side is shown) atboth ends in the axial direction. In opposition to this, an axial hole42 f is formed in the lower disk 42 b, and an axial hole 42 g is formedin the plate 42 c.

The carrier 42 and the planetary gear 43 are assembled in the followingmanner. First, the planetary gear 43 is assembled to the lower disk 42 bwhile the convex portion 43 a is fitted to the axial hole 42 f, and thenthe plate 42 c is assembled such that the convex portion 43 a is furtherfitted to the axial hole 42 g, and the through hole 42 e is engaged tothe protrusion 42 d of the column portion 42 a. Thereafter, the plate 42c can be fixed to the column portion 42 a by welding the protrusion 42 dusing, for example, an ultrasonic welding means. Since the axial holes42 f and 42 g and the convex portion 43 a are rotatable relative to eachother, the planetary gear 43 is freely rotatable with respect to thecarrier 42. It should be noted that the method of assembling the carrier42 is not limited to the above.

As can be seen in FIG. 2, each planetary gear 43 engages with the ringgear 44, and at the same time engages with the inner teeth of the outputgear 45 at one part (the lower portion). In FIG. 1, the rotational forceof the rotor assembly 8 decelerated by the deceleration mechanism 40 istransmitted to the output shaft 46 (the driver) of the feed screwmechanism 1 c through the output gear 45. An upper end of the outputshaft 46, which is made of stainless steel, is coaxially fixed to theoutput gear 45.

In the rotor assembly 8, a cylindrical body 202 serving as a peripheralwall and a sun gear member 204 disposed at the center are integrallymolded into a cylindrical shape with a top by a plastic material (here,PPS) that contains a magnetic material, and the rotor assembly 8 isrotatably disposed inside the can 30 by a shaft 201 that passes throughthe sun gear member 204 in the axial direction. As illustrated in FIG.2, the sun gear 41 is formed on the outer periphery of a cylinderimplanted in the center of the sun gear member 204. The ring gear 44 is,for example, a ring-shaped gear formed by molding plastic, and is fixedto an upper portion of a gear case 220, which is a cylindrical memberwhose lower portion is fitted to an upper portion of the valve main body10, as illustrated in FIG. 1.

According to such a configuration, when the sun gear 41 to which theoutput rotation of the electric motor is input rotates around itself,the planetary gear 43 engaged with the sun gear 41 and the ring gear 44revolves around the sun gear 41 while rotating. Since the planetary gear43 engages with the output gear 45 which is profile-shifted in relationto the ring gear 44, this rotation of the planetary gear 43 causes theoutput gear 45 to rotate at a very high deceleration rate relative tothe ring gear 44, for example, on the order of 50 to 1, depending on thedegree of profile-shift (the difference in the number of teeth). Aplanetary gear mechanism in which a planetary gear 43 engages with aring gear 44 and an output gear 45 in a profile-shifted relationship isreferred to as a mechanical paradox planetary gear mechanism.

According to the present embodiment, there is provided a sliding memberwhich abuts against the axial direction end of the sun gear 41, and thissliding member is formed of a different material than the sun gear 41.Therefore, since wear (primarily adhesion wear) does not occur fromsliding with the sun gear 41, it is possible to suppress the wear of thesun gear 41 without urging the sun gear 41 away from the carrier 42using a spring member or the like. Hereinafter, the sliding member willbe specifically described.

FIG. 4 is an enlarged view illustrating the inside of the can 30 in theconfiguration of FIG. 1. As illustrated in FIG. 4, the lower disk 42 bof the carrier 42 has a circular opening 42 h at the center thereofwhich passes through the shaft 201. In addition, the sun gear 41 throughwhich the shaft 201 penetrates in the axial direction has an annularboss 41 a at the tip (lower end), as partially illustrated in FIG. 2.

Further, a thin annular body 48 (illustrated by the hatching in FIG. 4)made of stainless steel is disposed between the annular boss 41 a andthe lower disk 42 b. The annular body 48 that serves as the slidingmember may be a washer that has the same diameter as the boss 41 a.

Referring to FIG. 1, the feed screw mechanism 1 c includes a cylindricalbearing 50, a screw shaft 52, and a ball 65. The lower end of thecylindrical bearing 50 is fitted into the valve main body 10, and isattached to the stepped portion 64 of the valve main body 10 in a stateof being supported via the upper flange portion 75 so as not to be ableto be pulled out from the valve main body 10 by means of press workingor the like.

The cylindrical bearing 50 supports the output gear 45 of thedeceleration mechanism 40 from the lower side at its upper end surface,and the output shaft 46 of the deceleration mechanism 40 is insertedinto the hollow upper portion of the cylindrical bearing 50. A malescrew portion 53 formed on the outer periphery of the screw shaft 52 isscrewed to the female screw portion 51 formed in the hollow lowerportion of the cylindrical bearing 50. In addition, a convex portion 54,which is a flat driver portion, is provided on the screw shaft 52 and isinserted into a slit-shaped concave portion 55 formed in the lower endportion of the output shaft 46 of the deceleration mechanism 40, andtransmits the rotation of the output shaft 46 to the screw shaft 52. Aconcave portion is formed in the lower end of the screw shaft 52, andthe ball 65 is fixed to the screw shaft 52 in a state in which it isfitted into the concave portion.

The rotation of the screw shaft 52 is converted into movement in theaxial direction by the screw action with the cylindrical bearing 50, andtransmitted to the valve shaft 60 side via the ball 65 and the ballbearing member 66. It should be noted that the screw shaft 52 may beprovided with a concave portion, and the output shaft 46 may be providedwith a convex portion inserted into the concave portion.

When the screw shaft 52 is moved in the valve opening direction in thefeed screw mechanism 1 c, in order to remove backlash between the femalescrew portion 51 and the male screw portion 53, the valve main body 10is provided with a coil spring 70 for urging the valve shaft 60 in thevalve opening direction. In order to support the coil spring 70, abottomed cylindrical spring support 73 made of metal is disposed in thevalve chamber 14. The spring support 73 includes a cylindricalperipheral wall 74 which opens and covers a circular space between theupper outer periphery of the valve shaft 60 and itself, an upper flangeportion 75 extending radially outward from the upper end, a lower flangeportion 76 extending radially from the lower end of the peripheral wall74 to the outer periphery of the valve shaft 60, and a cylindrical guideportion 78 extending coaxially with the valve shaft 60 from the lowerflange portion 76. The inner circumference of the guide portion 78slides with respect to the outer circumferential surface of the valveshaft 60, and forms a hole 77 for guiding the valve shaft 60.

The coil spring 70 disposed in the space between the valve shaft 60 andthe peripheral wall 74 is supported in a compressed state as a result ofits upper end abutting against the large diameter portion 67 of thevalve shaft 60 and its lower end abutting against the lower flangeportion 76 of the spring support 73. The upper flange portion 75 of theperipheral wall 74 is fixed by being interposed between the steppedportion 64 formed at the lower end of the valve hole 63 of the valvemain body 10 and the lower end of the cylindrical bearing 50 mounted inthe valve hole 63.

The valve shaft 60 is constantly urged in the valve opening direction(the direction of the feed screw mechanism 1 c) by the spring force ofthe coil spring 70 held in the compressed state in the spring support73, and when the valve shaft 60 is pushed down in the valve closingdirection by the force from the feed screw mechanism 1 c, the valveshaft 60 is lowered against the spring force of the coil spring 70, andthe valve member 61 formed at the distal end of the valve shaft 60 isseated on the valve seat 62 to close the orifice 16.

The screw shaft 52 can be rotated a small number of revolutions withrespect to the rotation of the rotor assembly 8, and the axialdisplacement of the screw shaft 52 corresponding to this rotation can becontrolled down to a small amount of displacement, so that the positionof the valve shaft 60 with respect to the valve seat 62 is positionedwith a high resolution by the gear deceleration unit 1 b, the flow patharea between the valve member 61 and the orifice 16 is controlled with ahigh accuracy, and the flow rate of the refrigerant passing therethroughcan be adjusted with a high accuracy. In other words, valve openingcontrol with high angular resolution is achieved. When operating thefeed screw mechanism 1 c in the valve opening direction, the valve shaft60 moves in accordance with the rise of the screw shaft 52 as a resultof the spring force of the coil spring 70,.

In the electrically operated valve illustrated in FIG. 1, refrigerant isintroduced into the can 30 through a minute gap between the inside ofthe guide portion 78 of the spring support 73 (the hole 77) and thevalve shaft 60, and a gap appropriately provided in the valve main body10, the cylindrical bearing 50, and the like. The minute gap between theguide portion 78 of the spring support 73 and the valve shaft 60 has aneffect of preventing foreign matter which may be contained in therefrigerant from entering the can 30.

In the electrically operated valve 1 of the present embodiment, theoutput gear 45 and the output shaft 46 move as one unit in therotational and axial directions. Since such a structure is provided, itis unnecessary to provide a complicated coupling structure between theoutput gear and the output shaft, and a simple electrically operatedvalve 1 can be provided.

The operation of the electrically operated valve 1 according to thepresent embodiment will be described. When electric power is suppliedfrom an external power source through the leads 14 in response to avalve opening signal, the stator 2 generates a magnetic force. The rotorassembly 8 is rotationally driven based on this magnetic force, andgenerates a rotational force in a predetermined direction. Thisrotational force is transmitted to the sun gear 41, decelerated via thedeceleration mechanism 40, and transmitted to the output gear 45.Further, since the rotational movement of the output gear 45 isconverted into the upward movement of the screw shaft 52 through thefeed screw mechanism 1 c, the valve shaft 60 urged by the spring forceof the coil spring 70 follows the upward movement of the screw shaft 52,and the valve member 61 separates from the valve seat 62 to allow thepassage of the refrigerant. On the other hand, when electric power ofthe inverse characteristic is supplied from an external power source viathe lead 142 in response to a valve closing signal, the valve shaft 60descends against the spring force of the coil spring 70 by a operationopposite to that described above, and the valve member 61 is seated onthe valve seat 62 to prevent passage of the refrigerant.

In the present embodiment, since the carrier 42 is mounted on the bottomsurface of the output gear 45, the carrier 42 and the planetary gear 43are also raised and lowered in accordance with the raising and loweringof the output gear 45.

In such a case, supposing that neither the prior art spring member northe annular body 48 were provided, the lower surface of the sun gearmember 204 provided on the rotor assembly 8 would come into contact withthe upper surface of the ring gear 44 and these surfaces would sliderelative to one another during the operation of the decelerationmechanism.

Accordingly, in order to prevent such a problem, in this embodiment, anannular body 48 made of stainless steel, which can be manufacturedrelatively inexpensively, is disposed between the boss 41 a and thelower disk 42 b as a sliding member. As a result, relative slidingoccurs results between the boss 41 a and the annular body 48, or betweenthe annular body 48 and the lower disc 42 b, but since the boss 41 a,the lower disc 42 b, and the annular body 48 are different materialsfrom each other, wear does not occur even under severe conditions, andit is possible to avoid premature wear of the boss 41 a.

Embodiment 2

FIG. 5 is a cross-sectional view of the inside of a can of anelectrically operated valve according to another embodiment. In thisembodiment, no annular body is used, and instead, the output shaft 46(illustrated by the hatching in FIG. 5) also serves as the slidingmember that slides to the boss 41 a of the sun gear 41. That is, theupper end portion of the output shaft 46 functions as the slidingmember.

More specifically, the circular opening 42 h provided at the center ofthe lower disk 42 b of the carrier 42 is made larger in diameter, andthe upper end of the output shaft 46 is extended upward to be fittedinto the circular opening 42 h. At this time, the upper end surface ofthe output shaft 46 that is exposed from the lower disk 42 b comes intocontact with the lower surface of the boss 41 a of the sun gear 41, andthese two surfaces slide with each other during the operation of theelectrically operated valve 1. Since the boss 41 a is made of PPS whilethe output shaft 46 is made of stainless steel, the two are made ofdifferent materials, such that wear does not occur during sliding, andpremature wear of the boss 41 a can be avoided. According to the presentembodiment, in addition to omitting the spring member of the relatedart, the wear of the boss 41 a can be suppressed without adding parts,and as a result, the assembly process can be simplified. The rest of theconfiguration is the same as that of the above-described embodiments.

It should be noted that, the present invention is not limited to theabove embodiments. Within the scope of the present invention, any of thecomponents of the above embodiments can be modified. In addition, anycomponent can be added or omitted in the above-described embodiments.

For example, although the annular body is made of stainless steel in theabove-described embodiments, it may be made of other metals, or may bemade of ceramic or glass.

REFERENCE SIGNS LIST

-   1 Electrically operated valve-   1 a Drive unit-   1 b Gear deceleration unit-   1 c Feed screw mechanism-   2 Stator-   8 Rotor assembly-   10 Valve main body-   14 Valve chamber-   16 Orifice-   20,22 Pipe-   30 Can-   40 Planetary gear type deceleration mechanism-   41 Sun gear-   42 Carrier-   43 Planetary gear-   44 Ring gear-   45 Output gear-   46 Output shaft-   48 Annular body-   50 Cylindrical bearing-   51 Female screw portion-   52 Screw shaft-   53 Male screw portion-   54 Convex portion-   55 Concave portion-   60 Valve shaft-   61 Valve member-   62 Valve seat-   63 Valve hole-   64 Stepped portion-   65 Ball-   66 Ball bearing member-   67 Large diameter portion-   68 Bearing member-   70 Coil spring-   73 Spring support-   74 Peripheral wall-   75 Upper flange portion-   76 Lower flange portion-   77 Hole-   78 Guide portion-   102 Dome portion-   140 Coil-   142 Lead-   180 Mounting bracket-   182 Hole-   201 Shaft-   202 Cylindrical body-   220 Gear case

1. An electrically operated valve comprising: a valve main body having avalve seat; a motor including: a stator fixed to the valve main body,and a rotor driven to rotate with respect to the stator, a planetarygear type deceleration mechanism configured to decelerate rotation ofthe rotor to transmit to an output gear; a valve member configured to bemovable toward and away from the valve seat in an axial direction; and afeed screw mechanism configured to convert rotational movement of theoutput gear into movement of the valve member in the axial direction;wherein: the planetary gear type deceleration mechanism includes: a sungear coupled to the rotor, a planetary gear engaged with the sun gear, acarrier for rotatably supporting the planetary gear, an annular ringgear engaged with the planetary gear, and a sliding member abuttingagainst an axial end of the sun gear, the output gear has a differentnumber of teeth than the ring gear, and engages with the planetary gear,the sliding member is made of a different material from the material ofthe sun gear, and the sliding member is: a washer-shaped annular bodydisposed between the sun gear and the carrier and is freely slidinglyrotatable with respect to both the axial end of the sun gear and thecarrier, or an output shaft that is connected to the output gear andslidingly rotates against the axial end of the sun gear.
 2. Theelectrically operated valve according to claim 1, wherein: the slidingmember is the washer-shaped annular body disposed between the sun gearand the carrier and is freely slidingly rotatable with respect to boththe axial end of the sun gear and the carrier.
 3. The electricallyoperated valve according to claim 2, wherein: the sun gear includes anannular boss disposed at an axial end thereof and the washer-shapedannular body abuts against the annular boss, a diameter of thewasher-shaped annular body being the same as a diameter of the annularboss.
 4. The electrically operated valve according to claim 2, wherein:the washer-shaped annular body is a stainless steel washer and theannular boss is a resin material.
 5. The electrically operated valveaccording to claim 1, wherein: the sliding member is the output shaftand slidingly rotates against the axial end of the sun gear, and thesliding member is connected to the output gear to transmit a rotationalforce to the feed screw mechanism.
 6. The electrically operated valveaccording to claim 5, wherein: the carrier includes a lower disk thatsupports one end of the planetary gear, and the output shaft extendsthrough a circular opening in the lower disk.
 7. The electricallyoperated valve according to claim 5, wherein: the output shaft is madeof stainless steel and the sun gear is made of a resin material.
 8. Theelectrically operated valve according to claim 1, further comprising: aplurality of planetary gears, each engaged with the sun gear, theannular ring gear, and the output gear, wherein the carrier includes alower disk, columnar portions disposed in parallel on an outer peripheryof an upper surface of the lower disk circumferentially between pairs ofthe plurality of planetary gears, and an annular plate arranged on topof the columnar portions; and ends of the planetary gears arerespectively held in the lower disk and the annular plate.
 9. Theelectrically operated valve according to claim 1, wherein: the sun gearis made of a resin material, and the sliding member is made of a metal,ceramic, or glass material.